1. Field of the Invention
The present invention relates generally to the field of measuring neurological impairment. The present invention specifically concerns presenting a battery of visual tests and recording a subject's eye position, eye movement, pupil dilation and pupil constriction to measure the severity of any traumatic brain injury.
2. Description of Related Art
Traumatic brain injury can be caused by head trauma after impact. The rapid acceleration or deceleration of the brain within the cranial vault, or absorption of a shock wave can cause the brain to impact the inside of the skull. These forces can also cause stretching and/or shearing of axonal tracts (tearing of connections between neuronal cells), which can trigger secondary neurodegenerative damage and maladaptive plasticity leading to chronic neurological dysfunction. The physiological effects resulting from these injuries can be detected immediately in some cases, but can also develop slowly over minutes, hours, weeks, months, or even years post-injury. Pathological processes can evolve slowly, making them difficult to detect in stages when interventions are most effective. Mild Traumatic Brain Injuries (mTBI) can result in post-concussion syndrome and impairment in cognitive domains such as memory, processing speed, affect, impulse control, prediction/planning and other executive functions as measured by traditional neuropsychological instruments. Acute physiological changes (e.g. inflammation) following mTBI may also make an individual more susceptible to a subsequent impact due to poor judgment or slower reaction times. These repeated impacts may, in turn, make an individual more susceptible to chronic neurological injury. Therapeutic options may be developed to prevent chronic neurological damage if we can identify reliable quantitative markers (changes in physiological and neurobehavioral responses) associated with mTBI. These quantitative measures could also be used in conjunction with acceleration measurements to identify those types of impacts associated with acute and chronic neurological injury. However, there are currently no devices capable of accurately and objectively tracking subtle changes in neurophysiological status associated with either mTBI or systems that accurately measure angular acceleration of the head correlated with mTBI biomarkers.
There is a critical need to identify a sensitive, rapid, easily obtainable biomarker to serve as an objective indicator of when an athlete should be withheld from play and when they can return to normal play in order to avoid permanent traumatic brain injury. Repeated concussive and even sub-clinical exposures to head trauma can produce a spectrum of chronic traumatic encephalopathy (CTE), resulting in stress points of damage in the brain, ranging in severity from mild cognitive impairment to severe dementia, disinhibited violent outbursts, motor dysfunction, reduced quality of life and even suicide. Oculomotor reactions in response to a pulse of light will reflect the status of the central nervous system following head trauma. Oculomotor reactions integrate a chain of neural events mediated by nerves passing through brain areas commonly affected by acute head trauma, and may also be affected chronically with repeated, mild head trauma which can by cumulative. This invention aims to show that the pupil light reflex and other oculomotor tests, unlike other measures of head trauma, are sensitive to acute, subclinical concussive forces and may also be used to inventory cumulative effects of mild head trauma over time, which fulfills a critical need in contact sports.